There exist today many designs of input devices for performing operations in a consumer electronic device. The movement of a conductive object such as a finger or stylus along a surface of the touch device is detected by the touch device to generate electrical signal for the subsequent process.
The touch sensing method may be based on resistive sensing, capacitive sensing, acoustic waving sensing, pressure sensing, optical sensing and the like. A touch on the surface of capacitive touch panel by a conductive object such as a finger or stylus results in the change in capacitance corresponding to the location of the touch. A processor connected to the touch panel interprets the coordinate of the touch depending on the change in capacitance.
A projective capacitive touch panel acting as a common type of capacitive touch panel normally includes a lattice electrode pattern. Referring to FIG. 1 and FIG. 2, the projective capacitive touch panel 1 comprising a substrate 6, a plurality of first electrodes 2, a plurality of second electrodes 3, insulator 4 and protective layer 5. The plurality of first electrodes 2 and the plurality of second electrodes 3 are intersected with each other to form a lattice pattern placed on the substrate 2. The insulator 4 is arranged between the two electrodes at the intersection of the plurality of first electrodes 2 and the plurality of second electrodes 3. The protective layer 5 covers all electrodes and insulator to protect them from been damaged. Also, a processor (not shown) is connected to the plurality of first electrodes 2 and the plurality of second electrodes 3. When a conductive object such as a finger or stylus is touching or moving on the projective capacitive touch panel, the signals associated with the electrodes is detected and transferred to the processor to interpret the position of the conductive object.
However, it is preferred that the capacitive touch panel, integrated with luminous device such as a display, be made of transparent materials since the lattice pattern is disposed on the visual area of display. The touch panel contains several layers of material with different refractive indexes. As a result, the light transmission of touch panel is limited, and the visibility of display is reduced. In addition, the protective layer in the conventional capacitive touch panel is of plane continuous structure to protect the weak intersection of electrodes. The amount of material used to make the protective layer is sizeable.
Thus, there is a need to improve on light transmission and material utilization of touch panels.